JP2001131620A - Smelting reduction method of iron oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smelting reduction method of iron oxide, with which the reducing temperature is low, the erosion of a refractory is not developed and the generation of CO gas is little. SOLUTION: Mixed raw material containing the iron oxide-containing raw material, slag-making agent and carbon is directly charged in molten iron 24 coexisting with the carbon at <=1,450 deg.C, and the iron oxide in the mixed raw material is reduced to produce the iron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the production of iron from iron oxide-containing raw materials by a smelting reduction method.

[0002]

2. Description of the Related Art Conventionally, iron production can be roughly divided into an iron source production method for producing iron by reducing iron oxide, and a scrap method using an electric furnace. Iron source production methods include a blast furnace method and a direct reduction method. The blast furnace method has a production scale of 2 to 3 million tons.
With the method of producing hot metal using large equipment,
Although the production efficiency is very high, there is a problem that the facility construction period is long, and the capital investment amount is extremely high at 2000 to 300 billion yen. In iron production, preliminary reduction of iron ore, which is a raw material, is not necessary.However, iron ore needs to have a certain size or more, and coke, which is a reducing agent, needs to be massive and have high strength. . For this reason, it is necessary to perform a pre-treatment of the raw materials such as producing sinter from iron ore or producing coke.

On the other hand, in an area where a large amount of natural gas can be used, a relatively small-scale production method assuming a production amount of 200,000 to 300,000 tons is not restricted by iron ore, and only iron ore is pelletized. The direct reduction method is adopted, which requires only raw material pretreatment. This direct reduction method requires a small capital investment of 10 billion yen and a reduction temperature of 800
Since the temperature is as low as ~ 1200 ° C, there is an advantage that the life of the refractory is long. However, there is a problem that preliminary reduction of iron ore as a raw material is necessary, and the cost is limited to an area where natural gas can be used at a low cost. In the gas reduction method, low melting point ferrite (2FeO.SiO) is generated,
In a rotary kiln, there is a problem of ring formation, and in a shaft furnace, there is a problem of shelf hanging during heating. Furthermore, in the fluidized bed method, the equipment efficiency per volume and the gas utilization rate are poor, and the obtained iron is an easily ignited iron called sponge iron. There is also the problem of becoming.

Therefore, the rotary hearth furnace method has been developed and is operating in several places. However, the heat supply is radiant, the rotary hearth furnace method determines the production amount by the thickness of the layer, and the reaction between the solid and the gas. Therefore, the reduction rate is low, the productivity is low, the temperature is difficult to control, and the welding phenomenon is likely to occur. Thus, the position as an iron source production method has not yet been established.

[0005] Therefore, as a method capable of using relatively low-grade iron ore or coke and capable of flexibly coping with a change in the production amount, the capital investment amount is assumed to be about 1 million tons, and A smelting reduction method has been developed as a method for producing hot metal of about 100 million yen.

[0006]

However, in the smelting reduction method, since the reduction temperature is as high as 1600 ° C., erosion of the refractory is severe, and the life of the refractory is a serious problem. In addition, since the smelting reduction method generates a large amount of CO gas during operation, effective use of CO gas and reconsideration of each step such as secondary combustion and preliminary reduction are necessary. It is considered to be an important point in gaining a legally established status, but there is still no clear solution. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for melting and reducing iron oxide, which has a low reduction temperature, has no refractory erosion, and has little CO gas generation.

[0007]

According to the present invention, there is provided a method for smelting and reducing iron oxide according to the present invention, which comprises mixing a raw material containing iron oxide, a slag-making agent and carbon with a mixture of carbon and 1.45 × 10
^It is directly introduced into molten iron at ³ ° C. or lower, and iron in the mixture raw material is reduced by carbon in the molten iron to produce iron. 1.45 × 10 ³ ° C. to promote the reduction reaction in the liquid phase in which the carbon in the molten iron participates in the reaction.
Also in the following, the reduction reaction rate can be kept high, and therefore, iron can be efficiently produced from various raw materials.

In the method for smelting and reducing iron oxide of the present invention, when the iron oxide in the raw material mixture is reduced by the carbon in the molten iron, the composition of the slag-making agent in the raw material mixture is adjusted. The components of the final slag to be generated are defined as (1) to (3) below, and the final slag is substantially 1.4.
It is preferable to form a protective layer on the refractory at the same time as ensuring the waste property at × 10 ³ ° C. (1) MgO ≦ 13% by weight and 15% by weight ≦ Al ₂ O
₃ + MgO ≦ 30% by weight (2) CaO / SiO ₂ ≦ 1.2 (3) 2% by weight ≦ FeO This makes it possible to stably melt and reduce iron oxide from a temperature range of 1150 ° C. or more, and The slag can maintain the operable liquid phase ratio.

In the method for smelting reduction of iron oxide according to the present invention, by adjusting the amount of carbon in the mixture raw material, the carbon content in the produced slag is 2% by weight or more and 10% by weight or less.
It is more preferable that the reduction of the iron oxide in the raw material mixture by carbon in the molten iron proceeds stably in the following manner. This makes it possible to cause the molten iron containing a saturated amount of carbon to be stably present and to prevent slopping.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is a conceptual diagram of a smelting reduction facility in a pot system to which the smelting reduction method of iron oxide according to one embodiment of the present invention is applied, and FIG. 2 is a smelting reduction facility in a drum system to which the smelting reduction method is applied. conceptual diagram, FIG. 3 is the relationship diagram of a temperature and a CaO / SiO ₂ on the existence of operational range, the relationship diagram between the temperature and FeO content in the slag 4 on the operating range, Figure 5 slag composition FIG. 6 is a material balance diagram at the time of manufacturing molten iron in the example of the present invention. Smelting reduction equipment to which the smelting reduction method of iron oxide according to one embodiment of the present invention is applied,
Batch type equipment and continuous drum type equipment can be roughly classified. Hereinafter, these will be described in detail.

As shown in FIG. 1, a pot-type smelting reduction apparatus 10 to which an iron oxide smelting reduction method according to an embodiment of the present invention is applied is charged with a mixture raw material, and the iron oxide contained in the mixture raw material is reduced. A pot 11a lined with a refractory, which is an example of a reaction vessel in which smelting reduction proceeds, a hopper 13 for storing iron ore, which is an example of a raw material containing iron oxide, and a hopper for storing coke, which is an example of carbon 14, a hopper 15 for storing slagging agent, and a mixture raw material supply device 12 including these transport pipes 16, an upper lid 11b of a pot 11a, and a heavy oil / oxygen burner which is an example of a heating device installed on the upper lid 11b. 18. Also, the top lid 11 of the pot 11a
b, a material inlet 17 to which a transport pipe 16 for the mixture raw material supplied from the mixture raw material supply device 12 is connected, a burner tuyere 19 for a heavy oil / oxygen burner 18, and a lance nozzle for supplying oxygen for coke combustion A lance port 21 for inserting a slag 20 and an exhaust port 22 for exhaust gas generated during the smelting reduction reaction are provided, and a molten iron 24 and a molten slag 25 for promoting a reduction reaction and improving heat transfer efficiency are provided at the bottom of the pan 11a. Tuyere 2 for supplying oxygen, which is an example of a gas for stirring, and carbon in the molten iron 24 used in the reduction reaction and reduced to the molten iron 24 to supply coke breeze, which is an example of carbon.
3 are installed.

Further, as shown in FIG. 2, a drum type smelting reduction apparatus 26 to which the smelting reduction method is applied is provided with a reaction vessel in which a raw material mixture is charged and smelting reduction of iron oxide in the raw material mixture proceeds. A drum 27 whose inner surface is lined with a refractory, a hopper 29 for storing iron ore, a hopper 30 for storing coke, a hopper 31 for storing slag forming agent,
It is an example of a mixture raw material supply device 28 provided with these transport pipes 32, a weir 37 for preventing molten iron 38 and molten slag 39 from flowing out, and a heating device installed on the outlet 34 side of the drum 27. And a heavy oil / oxygen burner 35. A transport pipe 32 for the mixture raw material supplied from the mixture raw material supply device 28 is connected to the inlet 33 side of the drum 27, and an exhaust port 36 for exhaust gas generated during the smelting reduction reaction is provided. Drum 2
Numeral 7 is inclined downward from the inlet 33 toward the outlet 34, and is rotated at a constant rotation speed around the center axis of the drum 27 by a rotating device (not shown). Therefore,
The mixture raw material charged in the drum 27 moves from the inlet 33 side to the outlet 34 side by the rotation of the drum 27, and is heated by the heavy oil / oxygen burner 35 provided on the outlet 34 side of the drum 27 during this time. You.

Next, the smelting reduction method of iron oxide according to one embodiment of the present invention is divided into a case where the pot type smelting reduction unit 10 and a drum type smelting reduction unit 26 are used.
This will be described in detail. 1. When using the pot-type smelting reduction equipment 10 First, iron and coke are used to produce molten iron 24 corresponding to 1/4 to 1/3 of the amount of molten iron that the pan 11a can hold and containing saturated carbon. The iron is melted by being charged in the pan 11a and heated by the heavy oil / oxygen burner 18 while blowing oxygen from the lance nozzle 20 into the pan 11a. After the formation of the molten iron 24, heating is continued with the heavy oil / oxygen burner 18 so that the molten iron state is maintained. Here, the mixture raw material is
Before charging the molten iron 24, the molten iron 24 is formed by the molten iron 2
This is because, by the presence of 4, the temperature of the mixture raw material charged in the pot 11a and the heat supply to the mixture raw material for the reduction reaction are efficiently performed.

A hopper 1 for storing iron ore in molten iron 24
3, using a mixture raw material supply device 12 from a hopper 14 for storing coke, and a hopper 15 for storing slag forming agent,
The mixed raw material is charged in an amount equal to or less than 1/3 of the whole charged amount. After charging the mixture raw material, the mixture raw material is heated by the combustion heat of coke by blowing oxygen from the lance nozzle 20 and the heavy oil / oxygen burner 18. Here, when the entire charged amount of the mixture raw material is loaded into the pan 11a at a stretch, the charged mixed raw material takes away the heat in the pan 11a, so that the initial charged amount is such that the generated molten iron 24 does not solidify. Amount, for example, an amount equal to or less than 1/3 of the entire charging amount.

The charged mixture raw material is suspended in the molten iron 24 and rapidly heated through the molten iron 24. When the temperature of the mixture raw material becomes 800 ° C. or higher, a part of the iron oxide in the mixture raw material starts to undergo a reduction reaction shown below with carbon in the molten iron 24 or coke in the mixture raw material, and the CO gas Occur, and the CO concentration in the atmosphere reaches 50%. Fe ₂ O ₃ + C (in molten iron 24) → 2FeO + CO (4) Fe ₂ O ₃ + C (coke) → 2FeO + CO (5) Fe ₂ O ₃ + CO → 2FeO + CO ₂ (6) In the mixed raw material suspended therein, the mixed raw material starts to float toward the surface of the molten iron 24 due to a difference in specific gravity between the mixed raw material and the molten iron 24, and during the floating process, (4) and (5)
Gradually progresses to form a slag containing a large amount of iron oxide. When the temperature of the mixture raw material reaches 1150 ° C., most of the iron oxide changes to FeO.

When the temperature of the raw material mixture becomes 1150 ° C. or higher, the slag containing a large amount of iron oxide begins to melt, and a part of the liquid phase / liquid represented by FeO (molten slag) + C (in molten iron 24) → Fe + CO This is an interphase reaction, the rate of the reduction reaction is high, and the reduction of iron oxide to iron begins to proceed rapidly. However, when the temperature range is 1150 ° C. or higher and lower than 1250 ° C., the liquid / solid phase reaction represented by FeO (mixture raw material) + C (in the molten iron 24) → Fe + CO 2 is still dominant, so that the amount of produced iron is a few. %, Which is a low value. At this time, oxygen gas for agitating the molten iron 24 and slag to promote the reduction reaction and improve the heat transfer efficiency, and powder for supplying the molten iron 24 with the reduced carbon in the molten iron 24 used for the reduction reaction. Coke is blown from tuyere 23 provided at the bottom of pan 11a.

When the temperature of the mixture raw material becomes 1250 ° C. or higher, the slag composition becomes (1) MgO ≦ 13% by weight and 15% by weight ≦ Al ₂ O
₃ + MgO ≦ 30% by weight (2) When CaO / SiO ₂ ≦ 1.2 is satisfied and the FeO content is 10% by weight or more,
Most of the slag is in the liquid phase. Therefore, the temperature range is 1
The main component of the reduction reaction at 250 ° C or higher is FeO (in molten slag) + C (in molten iron 24) → Fe + C
O 2, the rate of the reduction reaction is very high, and the iron oxide in the liquid phase of the slag is reduced to iron. Heating proceeds, and the temperature near the interface between the initially charged mixture raw material and the molten iron 24 becomes 1300.
When the temperature exceeds ℃, the liquid phase ratio of the slag 25 generated from the mixture raw material further increases, the reduction of iron oxide to iron proceeds rapidly, and iron is taken into the molten iron 24. Even in this case, when the ratio of CaO / SiO ₂ is 1.2 or more, the liquid phase ratio of the slag is reduced, and a problem of waste property occurs. FIG.
In addition, the temperature and CaO affecting the existence of the operable range when Al ₂ O ₃ + MgO = 20 wt% and FeO = 5 wt%
4 shows the relationship of / SiO ₂ . Here, the operable range is
The range in which the liquid phase ratio of the slag is high and the waste work can be performed.

Slag 2 generated as the reduction reaction proceeds
In No. 5, the FeO content in the slag 25 gradually decreases, and when the content becomes 10% by weight or less, the melting point of the slag 25 increases, and the liquid phase ratio of the slag 25 decreases even at a temperature of 1300 ° C. or more, The reduction reaction rate decreases. Therefore, it is difficult to reduce the reduction rate to, for example, 95% or more within a limited time range. On the other hand, when the temperature of the mixture raw material is close to 1400 ° C., even if the FeO content in the slag 25 is 2% by weight, the slag 25 can maintain the operable liquid phase ratio, and the range of the time is limited. Within this, a reduction rate of 95% or more can be achieved. FIG. 4 shows the relationship between the temperature and the FeO content in the slag, which affects the operable range. However, when the temperature of the mixture raw material is increased to such a high temperature, the reduction reaction rate can be increased. However, when the temperature exceeds 1400 ° C., the slag is finally completely melted, and The slag easily penetrates into the refractory used for the lining, and the refractory begins to melt. In order to achieve a reduction ratio of 95% or more within a limited time, the temperature of the mixture raw material should be kept as high as possible within a range that does not cause erosion of the refractory. . For this reason, the upper limit of the slag temperature is 1400 ° C.
However, the erosion of refractories begins to become significant,
Since the slag temperature has exceeded 1450 ° C., the operation can be performed with the slag temperature raised to 1450 ° C. Therefore, the upper limit of the slag temperature is 1450 ° C., preferably 1400 ° C., and the upper limit of the temperature of the molten iron coexisting with carbon is also 1450 ° C., preferably 1400 ° C.
Further, in a temperature range of 1350 ° C. or more and 1450 ° C. or less, since a solid phase partially remains in the final slag 25,
Slag coating (formation of a protective layer) on the refractory used for the lining of the pot 11a is possible, and the life of the refractory can be greatly extended. FIG. 5 shows the temperature of the final slag 1400 ° C., CaO / SiO ₂ ≦ 1.2, ₂ % by weight.
Slag composition (MgO, Al
The relationship between ₂ O ₃ ) and the operable range is schematically shown.

When the temperature is 1150 ° C. or more, 1400 ° C.
In the range below ℃, the iron generated by reduction is slag 2
The carbon excessively contained in 5 is melted to become molten iron having a low melting point, taken into molten iron 24 and separated from slag 25. In the above reduction reaction, the carbon in the molten iron 24 is
Acting as a reducing agent for iron oxide, the carbon in the molten iron 24 is reduced by the amount used for the reduction. However, if the amount of carbon in the mixture raw material is controlled so that the carbon content in the slag 25 is 2 to 10% by weight, the carbon content reduced from the molten iron 24 is transferred from the slag 25 to the molten iron 24. Since it is always supplied, the carbon in the molten iron always maintains a constant ratio and contributes to the continuation of the reduction reaction. Slag 25 and molten iron 24
When the mixture raw material is supplied directly from above the pot 11a in accordance with the speed at which the reduction proceeds at the interface with, the reduction reaction proceeds continuously, and the iron oxide in the mixture raw material is reduced to iron. . In this case, it is necessary to adjust the energy supply rate and the mixture material supply rate so that the temperature of the molten iron 24 does not exceed 1450 ° C. As a guide, the energy supply is two times the theoretical energy required for the smelting reduction of the mixture raw material.
Experiments have shown that less than twice the energy is sufficient.

When the charging of the predetermined amount of the mixture raw materials is completed and they are substantially reduced and the production of iron is completed, the operation proceeds to tapping operation and waste disposal operation. It does not matter which of the tapping operation and the tailing operation is performed first.
About 2/3 of the molten iron 24 produced in a is tapped, and the remaining about 1/3 is left in the pan 11a. In addition, in order to ensure the workability of the slag 25 to be discharged, the temperature is 1350 ° C. or more, and 1450 ° C. or less from the viewpoint of protection of refractories.
Preferably, it is necessary to maintain the temperature of the slag 25 at 1400 ° C. or less.

By allowing the molten iron 24 to remain in the pot 11a, the next raw material mixture can be charged into the pot 11a and the production of iron can be continued without going through the step of generating molten iron again. . At this time, the temperature of the molten iron 24 is set to 1350 ° C. or more so that the refractory does not melt and the heating and reduction of the mixture material proceed easily when the next mixture material is charged. It is preferable to control the temperature within a range of 1450 ° C. or less. In addition, in the charging of the mixture raw material after the next time, the slag 25 is charged into the pot 11a as an initial charging amount of 1/3 or less of the total charging amount of the mixture raw material.
The same charging method as the initial charging of the raw material mixture is repeated, in which the remaining raw material mixture is supplied from above the pot 11a in accordance with the speed at which the reduction of the iron oxide proceeds at the interface between the raw material and the molten iron 24. . The reason is to prevent solidification of the molten iron 24.

2. First, iron and coke are charged into the drum 27 and heated by the heavy oil / oxygen burner 35 so that a fixed amount of molten iron 38 is always present over the entire length of the drum 27. . Here, the reason why the molten iron 38 is generated in advance is that if the molten iron 38 is present, it is possible to efficiently raise the temperature of the mixture raw material charged into the drum 27 and efficiently supply heat to the mixture raw material for the reduction reaction. It is possible. A hopper 29 for storing iron ore and a hopper 3 for storing coke in the generated molten iron 38.
0, and the mixture raw material is supplied from the hopper 31 for storing the slag forming agent to the entrance 3 of the drum 27 by using the mixture raw material supply device 28.
Load from 3 side. At this time, it is necessary to supply a sufficient amount of heat to the molten iron 38 by burning the coke and heating the heavy oil / oxygen burner 35 so that the molten iron 38 is not solidified by charging the mixture raw material. The charging amount of the mixture raw material is limited by the amount of heat supplied by the combustion of coke and the heating of the heavy oil / oxygen burner 35.

Since the drum 27 is inclined from the inlet 33 to the outlet 34, the mixture material charged by the rotation of the drum 27 moves from the inlet 33 to the outlet 34. The charged mixture material is supplied from the inlet 33 side to the outlet 34 side.
While moving to the side, heating from molten iron 38, burning coke,
Heating is performed by heating by the heavy oil / oxygen burner 35 and radiation from the furnace wall refractory of the drum 27. When the temperature of the mixture raw material exceeds 1000 ° C., a reduction reaction starts in a part of the mixture raw material, but the reaction rate is slow. Further, when the temperature of the mixture raw material exceeds 1300 ° C., the mixture raw material is melted and liquefied, and is rapidly reduced by the carbon in the molten iron 38. The iron generated by the reduction is taken into the molten iron 38 and further combined with excess carbon to form a molten iron 38 having a low melting point. The mixed raw material is separated into the molten iron 38 and the slag 39, and the slag 39 is separated from the molten iron 38 by a specific gravity difference. Remain on top.

As the reduction reaction proceeds, FeO in the mixture raw material
The content decreases, the melting point of the produced slag increases, the liquid phase ratio of the slag decreases, and the speed of the reduction reaction decreases. Therefore, the composition of the final slag 39 is as follows: (1) MgO ≦ 13% by weight and 15% by weight ≦ Al ₂ O
₃ + MgO ≦ 30% by weight (2) If the composition of the slag-making agent in the mixture raw material is adjusted so that CaO / SiO ₂ ≦ 1.2, it is possible to operate in a temperature range of 1450 ° C. or less, preferably 1400 ° C. It is possible to ensure a proper slag liquid phase ratio.

In this manner, the mixture material charged into the drum 27 is supplied from the inlet 33 side of the drum 27 to the outlet 34.
While moving to the side, it is heated and reduced, and becomes molten iron 38 and slag 39 at 1400 ° C. near the outlet 34 side of the drum 27. Since the weir 37 is provided on the outlet 34 side of the drum 27, the molten iron 38 and the slag 39 overflow the weir 37 and are continuously discharged from the drum 27. At this time,
Since the drum 27 is rotating, the molten iron 38 and the slag 39
The molten iron 38 and the slag 39 have different positions at which they overflow the weir 37 due to differences in density, viscosity, and the like, and the molten iron 38 and the slag 39 are separated and continuously discharged. In addition, in order to ensure the workability of discharging the final slag 39, 1450 ° C. or less, preferably 1400 ° C.
It is preferable to control the liquid phase ratio of the slag 39 at a temperature equal to or lower than a temperature within a range in which the slag 39 can be operated. Here, the reason for setting the upper limit temperature of the slag 39 to 1450 ° C. or less, preferably 1400 ° C. or less is that when the slag temperature exceeds 1450 ° C., the slag 39 is completely melted and the refractory used for lining the drum 27 is used. This is because the slag 39 easily penetrates into the inside, and the erosion of the refractory begins to become significant.

When the liquid phase ratio of the slag 39 is properly controlled, slag coating can be performed on the surface of the refractory used for the lining of the drum 27, thereby protecting the slag from erosion of the refractory. Can be carried. The temperature of the fixed amount of molten iron 38 always present over the entire length of the drum 27 is set to 1350 so that the slag 39 does not cause erosion of the refractory and heating and reduction of the charged mixture material can easily proceed. The temperature is controlled to be in a range of not less than 1 ° C. and not more than 1450 ° C., preferably not more than 1400 ° C.

[0027]

EXAMPLE Iron ore and coke having the composition shown in Table 1 are used, and a unit of coke is set to 400 kg / molten iron t.

[0028]

[Table 1]

From the composition of iron ore and coke shown in Table 1, assuming that the reduction ratio of iron oxide is 98%, the iron ore required for producing 1 t of molten iron is 1593 kg. When using 1593 kg of iron ore and 400 kg of coke, the content of each component contained in the iron ore and coke is calculated, as shown in Table 2. Table 3 shows the final slag component obtained from Table 2.

[0030]

[Table 2]

[0031]

[Table 3]

From Table 3, it can be seen that MgO ≦ 13% by weight and 15%
Since it is known that the conditions of wt% ≦ Al ₂ O ₃ + MgO ≦ 30 wt% and 2 wt% ≦ FeO are satisfied, the slag-making agent required for adjusting the final slag composition is C
111 k required to adjust aO / SiO ₂ = 1
g of CaO only. Molten iron was manufactured using the ladle-type smelting reduction facility 10 based on the results of the examination of the adjustment of the mixed raw materials described above. The composition of the obtained molten iron 1t was 96% by weight of iron and 4% by weight of carbon, and the slag generated at that time was 314 kg. FIG. 6 shows the relationship between the material balances during the production of molten iron at this time.

The embodiment of the present invention has been described above.
The present invention is not limited to this embodiment,
For example, in the pot-type smelting reduction facility 10, heating is performed by a heavy oil / oxygen burner 18, and oxygen gas is blown into the molten iron and slag for agitation in order to promote a reduction reaction and improve heat transfer efficiency. Alternatively, arc heating by electric energy can be employed as a heating method, and other gases such as argon gas and nitrogen gas can be blown into the molten iron and slag for stirring. In the drum type smelting reduction facility 26, the heavy oil / oxygen burner 35 is installed on the outlet 34 side, but may be installed on the inlet 33 side. In addition, as the iron oxide-containing raw material, in addition to iron ore, fine ore and lump ore, iron oxide dust generated in large quantities in various production facilities of an ironworks, and carbon-containing materials such as waste plastics as carbon can also be used. .

[0034]

According to the method for smelting reduction of iron oxide according to any one of the first to third aspects, a raw material containing iron oxide, a slag-making agent and carbon is directly introduced into molten iron at 1450 ° C. or lower coexisting with carbon. Then, the iron oxide is reduced by reducing the iron oxide in the mixture raw material by the carbon in the molten iron, so that there are few restrictions on the raw material, the generation of CO gas is small, and the use of low-grade raw material is possible. Little pre-processing is required. Further, even when the water content of the raw material is large, the charging of the raw material can be performed only by lowering the supply rate of the raw material or reducing the water content to about 10%. Furthermore, since the equipment construction cost is low, it is used as a facility for reducing and using fine ore generated at the yamamoto and exporting it as molten iron, and as an iron source manufacturing facility for a 20 to 300,000 t / year mini-mill. Use is also possible.

In particular, in the smelting reduction method of iron oxide according to claim 2, when the iron oxide in the mixture raw material is reduced by the carbon in the molten iron, the composition is adjusted by adjusting the composition of the slag-making agent in the mixture raw material. (1) MgO ≦
13% by weight and 15% by weight ≦ Al ₂ O ₃ + MgO ≦ 3
0% by weight, (2) CaO / SiO ₂ ≦ 1.2, (3) 2
Assuming that the weight% ≦ FeO, the final slag is substantially 1400
At the same time, the smelt reduction temperature is lower than the conventional smelting reduction temperature, the running cost of the equipment is lower, and the molten iron and slag are separated. The slag is also easily discharged. Also,
Since the slag is in a semi-molten state, the slag can be coated on the refractory for lining the reaction vessel, and the life of the refractory can be extended several times.

In the method for smelting and reducing iron oxide according to claim 3, the amount of carbon in the slag formed is adjusted to 2% by weight or more and 10% by weight or less by adjusting the amount of carbon in the mixture raw material. Since the reduction of iron oxide in the mixture raw material by carbon in the mixture proceeds stably, molten iron containing a saturated amount of carbon can be stably present, and the heat transfer efficiency to the mixture raw material and the reduction of iron oxide It is possible to increase the speed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a smelting reduction facility in a pot system to which a smelting reduction method of iron oxide according to an embodiment of the present invention is applied.

FIG. 2 is a conceptual diagram of a smelting reduction facility in a drum system to which the smelting reduction method is applied.

FIG. 3 shows the effect of temperature and CaO /
FIG. 3 is a diagram showing the relationship between SiO ₂ and SiO ₂ .

FIG. 4. Effect of temperature and Fe in slag on operable range
It is a relation figure with O content.

FIG. 5 is a relationship diagram between slag composition and operable range.

FIG. 6 is a material balance diagram at the time of manufacturing molten iron in an example of the present invention.

[Explanation of symbols]

10: Pan-type smelting reduction facility, 11a: Pan, 11b: Top lid, 12: Mixture raw material supply device, 13, 14, 15: Hopper, 16: Transport pipe, 17: Raw material loading inlet, 18:
Heavy oil / oxygen burner, 19: burner tuyere, 20: lance nozzle, 21: lance mouth, 22: exhaust outlet, 23: tuyere, 24: molten iron, 25: slag, 26: drum type smelting reduction facility, 27: drum , 28: mixture raw material supply device,
29, 30, 31: hopper, 32: transport pipe, 3
3: inlet, 34: outlet, 35 heavy oil / oxygen burner, 3
6: exhaust port, 37: weir, 38: molten iron, 39: slag

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Saburo Sato 1-3-1 Otani, Yawatahigashi-ku, Kitakyushu-shi, Fukuoka F-term (reference) 4K001 AA10 DA01 HA01

Claims (3)

[Claims] 1. A raw material mixture containing iron oxide-containing raw material, a slag-making agent, and carbon is directly introduced into molten iron of 1.45 × 10 ³ ° C. or less coexisting with carbon, and the mixture is mixed with carbon in the molten iron. A method for reducing iron oxide by reducing iron oxide in a raw material to produce iron. 2. The method for smelting and reducing iron oxide according to claim 1, wherein when the iron oxide in the raw material mixture is reduced by the carbon in the molten iron, the composition of the slag-making agent in the raw material mixture is adjusted. The components of the final slag to be generated are defined as (1) to (3) below, and the final slag is 1.4 × 10 ³
A method for smelting and reducing iron oxide, which comprises forming a protective layer against refractories at the same time as securing the waste property at a temperature of ° C. (1) MgO ≦ 13% by weight and 15% by weight ≦ Al ₂ O
₃ + MgO ≦ 30% by weight (2) CaO / SiO ₂ ≦ 1.2 (3) 2% by weight ≦ FeO 3. The method for smelting and reducing iron oxide according to claim 2, wherein the carbon content in the produced slag is adjusted to 2% by weight or more and 10% by weight or less by adjusting the amount of carbon in the mixture raw material. And reducing the iron oxide in the raw material mixture by the carbon in the molten iron in a stable manner.